Advanced Cell Diagnostics’ RNAscope® platform is fast becoming a routinely used method for gene expression analysis. ACD has nearly 9000 target RNA-specific probes in use and there are over 400 publications with the method. RNAscope® is enabling faster and more rigorous target analysis; it is a robust and ultra-sensitive RNA in situ hybridization (RNA ISH) method providing single-cell and single-molecule RNA detection in the context of complex disease microenvironments. ACD’s proprietary oligo probe design and amplification methods result in a universal assay that is as sensitive and specific as RT-PCR and provides cellular resolution and tissue context. RNAscope® detection limit is significantly lower than IHC and has been clinically validated; it has enabled patient selection in clinical trials and ACD has partners for CDx development. The technology and illustrations of published application will be presented.